Asus X555LD Rev 3.3 startuje na baterii nie startuje na zasilaczu

Witam,

Na stole laptop Asus z płytą X555LD rev 3.3 która nie startuje na zasilaczu ale startuje na baterii. Wymieniony przebity mosfet PQ8802. (Wymieniłem obydwa na FDMC8884) Wymienione BQ735 żadnych zmian na starym BQ735 takie same pomiary. Połączenia pomiędzy BQ a mosfetami są ok. Gdy zrobię zworę na PQ8801 wszystko działa. Nie mogę namierzyć żadnego zwarcia. Pomiary BQ następujące:

1. 1,9V - 3,6V pływa
2. 1,9V - 3,6V pływa
3. 0V
4. 0-0.1V
5. 0
6. 2,58V
7. 0V
8. 0,1V - 0,5V
9. 0,1V 0 0,5V
10. 1,4V
11. 2,3V-3,7V
12. 2,4V-3,9V
13. 2,4V-3,9V
14. 0V
15. 0V
16. 6.09V
17. 5.92V
18. 2,4V-3,9V
19. 2,4V-3,9V
20. 18,70V - 18-74V

Czytałem wszystkie wątki związane z tą płytą i takiego przypadku nie znalazłem.
Proszę o sugestię z góry dziękuję i pozdrawiam.
Łukasz

Podmień PQ8801.

Wymieniłem dla pewności obydwa ponownie PQ8801 i PQ8802 i teraz efekt taki że tylko migną diody. Napięcia nie pływają. ale płyta dalej nie startuje na zasilaczu. Na samej baterii wciąż działa.

Ponów pomiary napięć do masy na pinach 1, 3, 4, 5, 6, 11, 12, 18 i 20 chargera PU8800 z podłączonym tylko zasilaczem, bez baterii.

1 - 1,6-3,2V pływa
3 - 0-0,1V pływa
4 - 0-0,1V pływa
5 - 0
6 - 2,59V
11 - 0-5V pływa
12 - 1,7-3,6V pływa
18 - 1,6 -3,45V pływa
20 - 18,90V

Measure the resistances between listed pins:
a) Between pin 1 and pin 2 of charger chip.
b) Between pin 12 and pin 13 of charger chip.
c) Between pin 12 and pin 19 of charger chip.
d) Between pin 1 of charger chip and pin 5 of PQ8802.
e) Between pin 3 of charger chip and pin 1 of PQ8801.
f) Between pin 4 of charger chip and pin 4 of PQ8801.
g) Between pin 4 of PQ8801 and pin 4 of PQ8802.

Pomiary jak poniżej:

a) Between pin 1 and pin 2 of charger chip = 1,3 Ohm
b) Between pin 12 and pin 13 of charger chip = 22.6 kOhm
c) Between pin 12 and pin 19 of charger chip = 10,4 Ohm
d) Between pin 1 of charger chip and pin 5 of PQ8802 = 1,4 Ohm
e) Between pin 3 of charger chip and pin 1 of PQ8801 = 4 kOhm
f) Between pin 4 of charger chip and pin 4 of PQ8801 = 4 kOhm
g) Between pin 4 of PQ8801 and pin 4 of PQ8802 = 0,4 Ohm

Pozdrawiam
Łukasz

lukaskrus wrote:b) Between pin 12 and pin 13 of charger chip = 22.6 kOhm

Correct value: 16.8Ω
Check the resistors PR8821 (10Ω) and PR8824 (6.8Ω).

lukaskrus wrote:c) Between pin 12 and pin 19 of charger chip = 10,4 Ohm

Correct value: 6.8Ω
The resistor PR8824 is also likely to blame here.

Now i read
Between pin 12 and pin 13 of charger chip 17.4 Ohm
Between pin 12 and pin 19 of charger chip = 7,3 Ohm

The PR8824 measured value is 7.4 Ω
The PR8821 measured value is 10,4 Ω

Laptop still not starting and i can hear a clicking sound 1,5 between every 1,5 second.
What else i can check ?

Check your solder joints on all pins of charger chip.

I've put another brand new PU8800 and it is the same story. I think there is short somewhere but i can't find where it could be.
I have shortened PQ8801 for a test and it is also not starting. I've tried with connected battery and on PD8802 pin 1 there was 19 volts (with PQ8801 shorted) and and after 30 seconds there was a voltage drown for 3A and voltage drop to 10V for 2 seconds and and 30 seconds later again voltage drop.

lukaskrus wrote:I have shortened PQ8801 for a test and it is also not starting.

There is a risk to burn the transistor PQ8802 this way, because the current flows through the "body diode" of PQ8802. This current may be grater than the "body diode" can handle.

lukaskrus wrote:I've tried with connected battery and on PD8802 pin 1 there was 19 volts (with PQ8801 shorted) and and after 30 seconds there was a voltage drown for 3A and voltage drop to 10V for 2 seconds and and 30 seconds later again voltage drop.

Never do this again, as there is a risk to damage the battery (it may even explode) this way.

You should't do such a stupid things with your service level = 3

However, remove the bridge on transistor PQ8801 and replace the transistor PQ8802 as you may have burnt it. Then perform the following measurements.
- Measure the voltages to ground on pins 1, 2, 3, 4, 5, 6, 8, 9, 11, 12, 13, 16, 17, 19, 20 of charger chip with the power supply + battery connected to the board.

Yes it was stupid what i did

I was looking again on the schematic and i found shorted D-S on PQ8804 i have replaced it togheter with PQ8802.


Scenario is battery is connected and when i plug charging cable current is rising for a second to 0,52A and goes to 0.01A, laptop turns on and measurements are as follows on charger(battery is not charging):

1 - 7,64
2 - 7,64
3 - 0,353
4 - 0,208
5 - 2,98
6 - 2,63
8 - 0
9 - 3,2
11 - 13,4
12 - 7,59
13 - 7,59
16 - 6.08
17 - 7,33
19 - 7,58
20 - 19,20

- Replace the transistor PQ8805 regardless of whether it seems functional or not.

Measure the following resistances between listed pins of charger chip (with the battery disconnected of course):
- Between pin 14 and pin 15.
- Between pin 14 and pin 16.
- Between pin 15 and pin 16.
- Between pin 17 and pin 18.
- Between pin 17 and pin 19.
- Between pin 18 and pin 19.

PQ8850 replaced.
Measurments are as follows:

- Between pin 14 and pin 15 - 192,4 kΩ
- Between pin 14 and pin 16 - 329,6 kΩ
- Between pin 15 and pin 16 - 360,8 kΩ
- Between pin 17 and pin 18 - 1,6 MΩ
- Between pin 17 and pin 19 - 1,1 MΩ
- Between pin 18 and pin 19 - 205,2 kΩ

Regards
Luk

Check your solder joints on all pins of charger chip.

Hello,

It was as you suggested bad soldering. I have removed BQ clean pads again put new solder on BQ and soldered it back and it worked.
Board is starting and battery is charging.
A lot of thanks for the help of Vogelek and matic

Best regards
Luk